Clinical practice in obstetrics has sometimes been incorporated without adequate study of efficacy and the potential risks of such interventions. With development of new technologies and interventions to reduce perinatal complications, there is a need for well designed scientific studies of adequate size to evaluate the efficacy, risks, and benefits before they are incorporated into practice. Since its inception, the NICHD Maternal-Fetal Medicine Units (MFMU) Network has brought important understanding regarding prediction and prevention of complications related to preterm birth (Preterm Prediction Study, progesterone to prevent recurrent preterm birth, antibiotics for preterm premature rupture of the membranes, treatment of asymptomatic bacterial vaginosis and Trichomonas vaginalis, home uterine monitoring, repeated antenatal corticosteroids before preterm birth). The NICHD-MFMU Network has taken a leading role in the study of other pregnancy complications and clinical issues (prevention of preeclampsia, fetal pulse oximetry in labor, treatment of mild gestational diabetes, vaginal birth after cesarean, Factor V Leiden mutation carriage). The goal of this application is to demonstrate that the Department of Reproductive Biology at Case Western Reserve University (CASE) has participated successfully and is qualified to continue in the NICHDMFMU Network. Our investigators have strong backgrounds in clinical research, including multicenter studies, those involving neonatal and long term infant follow-up, and many of the above NICHD-MFMU Network studies. CASE-MetroHealth Medical Center (MHMC) investigators have provided leadership in the development and conduct of NICHD-MFMU Network studies and have actively participated in and led the administrative committees needed for the successful conduct and dissemination of the results for these studies. CASE and MHMC have provided a stable administrative, clinical and research infrastructure needed to support the conduct of NICHD-MFMU Network studies, including our General Clinical Research Center immediately adjacent to our Labor &Delivery and NICU suites. Our computerized perinatal database (extending back to 1974) and our electronic medical record (EPICARE from 2001) are excellent resources to assist in the design and conduct of clinical research. Our MFM and Neonatology researchers have a demonstrated ability to conduct collaborative research and are committed to the success of this Network. The NICHD-MFMU Network will continue to lead the evaluation of established and new technologies and interventions in obstetric practice, particularly those requiring multi-center study. CASE-MHMC will continue to contribute successfully to this Network, and offers strengths needed to successfully participate in studies that will directly change practice and reduce morbidity related to pregnancy complications nation-wide and world-wide.